Recently, in a corporate Information Technology (IT) system or data center, it is becoming general to utilize extensible Markup Language (XML) messages, for example, in Simple Object Access Protocol (SOAP) for data communication between applications.
In such a system, when the applications process XML messages in the same format, there is no problem, and when XML messages in different formats are processed, either application may be changed, or a message relay apparatus for converting messages may be provided between the applications.
Here, when the latter is selected, the message relay apparatus typically includes a dedicated arithmetic unit (e.g. XML accelerator) for accelerating speed of a conversion processing of the messages, and the dedicated arithmetic unit executes the XML conversion processing, and a general-purpose processor executes a transfer processing.
However, the processing load of the XML conversion processing tends to be high, and in a large-scale system, there is a possibility that the message relay apparatus becomes a bottleneck. Therefore, by introducing a Layer-4 switch (L4SW) and plural message relay apparatuses to perform the load balancing of the message relay apparatuses, it tries to improve the throughput of the overall system.
At this time, because the load balancing in the Layer-4 switch is carried out based on the load of the general-purpose processor in the message relay apparatus, the balance of the loads for the dedicated arithmetic units is not considered. Therefore, a problem that the throughput of the overall system becomes lower may occur. More specifically, because contents of the XML conversion depend on the messages, inefficiency may occur when a lot of messages whose load of the XML conversion processing is little are allocated to one message relay apparatus, and reversely, when a lot of messages whose load of the XML conversion processing is large are allocated to one message relay apparatus.
In other words, when messages in different formats are converted and relayed by a message relay apparatus, the throughput in the overall system may become low in the conventional system.